Bicknell hall



(No Model.) v

B. HALL.

TUBE FOR USE IN EXPANSION JOINTS. No. 530,305. Patented Dec. 4, 1894.

UNITED STATES PATENT OFFICE.

BICKNELL HALL, or TAU omMAssAoHUsETTs, ASSIGNOR or ONE-THIRD TO EDWARDP. COLEMAN, OF SAME PLACE.

TUBE FO USE IN EXPANSION-JOINTS.

SPEGIFIOATION forming part of Letters Patent No. 530,305, registeredDecember 4, 1894.

Application filed August 24, 1894- To all whom it may concern.-

Be it known that I, BICKNELL HALL, of Taunton, in the county of Bristoland State of Massachusetts, have invented a new and useful Improvementin Tubes for. Use in Expansion-Joints, so-called, Condensers andFeed-Water Heaters, and the Like, of which the following is aspecification.

My invention is an improvement on the corrugated tube which has beenextensively used under the circumstances referred to to take up theexpansion and contraction due to changes of temperature.

From long experience I have found that when a piece of corrugated tubingis constantly expanding and contracting a very. large percentage of thebending dueto expansion and contraction falls upon thosecorrugationswhich are Weaker or thinner than the others so that the wear is notdistributed equally and the tube wears out sooner than itshould.

My invention is intended to remedy this fault and it consists in a pieceof tubing which is not corrugated but is indented in lines across theaxis of the tube by a series of short indentations which are so arrangedthat each indentation breaks joints with the indentations on each sideof it and is separated at each end from the next indentation in line bya blank space, the natural curvature of the tube.

My invention will be understood byreference to the drawings, in whichFigure 1 is an elevation partlyin section of a piece of tubing embodyingmy invention, Fig. 2 being a cross section on line 2 2 of Fig. 1.

A represents the indentations above described, B being the portions ofplain tube lying between the ends of the indentations and 0 being thoseportions of the plain tube which lie between the lines of indentations.In cross section these indentations are preferably curved as will beunderstood from Fig. 1, but the length of each indentation is less thanthe circumference of the tube so that each indentation extends only partway SerialNo. 521,255. (No model.)

round the tube. In the drawings each inden tation is somewhat less inlength than a quar- 5o ter of the circumference of the tube and eachindentation breaks joints so to speak, with the indentations'in the linenext it on each side. By this means I find that the strain tending tochange the length of these tubes is 'dis- 5 5 t-ributed very evenlythroughout the length of tube.

The number of indentations may well depend upon the diameter of the tubeor upon the thickness of the metal, and the lines of 6c indentations maybe annular as shown or a spiralline of indentations may be used, withsubstantially the same result. I prefer for general use however, theannular indentations, four in numberas shown. Such a tube as I havedescribed may be made upon a collapsible grooved mandrel which is set upin a turning lathe so as to be rotated. The tool is an ordinary rollerof proper dimensions to form the indentation, a portion of the peripheryof the tool being removed so as to leave the part B of the tubeuntouched. This tool is mounted in a tool stock in the ordinary way andheld against the tube. 7 5

The process of manufacture will be easily understood in all its detailsby those skilled in tube working. 7

What I claim as my invention is as follows:

1. The tube above described provided with a series of indentations lyingin a line or lines across the axis of the tube, each indentation beingless in length than the circumference of the tube, as set forth.

2. The tube above described provided with a series of indentationsarranged in a line or in lines across the axis of the tube, eachindentation being separated from the indentation at each end of it'andbreaking joints with the indentations at each side of it, as set forth.

In testimony whereof I have hereunto set my hand this 14th day ofAugust, 1894:.

BIOKNELL HALL.

Witnesses:

PERCY U. KENWAY, GEORGE O. G. CoALE.

